Preparation of nanospinels NiMnxFe2−xO4 using sol–gel method and their applications on removal of azo dye from aqueous solutions

In this paper, nanospinels NiMn_xFe_2−xO₄ (x = 0.05, 0.1, 0.3, 0.5, 0.7, and 1) were prepared by sol–gel method in the presence of nitrate–metal–ethylene glycol (EG) polymerized complex. The nanospinels were characterized using thermogravimetry analysis (TGA), X-ray powder diffraction (XRD), Fourier infrared spectroscopy (FTIR), and transmission electron microscope (TEM). The adsorption of an azo dye, reactive blue 5 (RB5), from water was determined using the prepared nanospinels. The effect of operational parameters such as the initial dye concentration, the concentration of nanospinels, temperature, and pH on the degradation of dye was investigated. The adsorption process follows second-order kinetics and Arrhenius behavior. Two common models, the Langmuir and Freundlich isotherms were used to investigate the interaction of dye and nanospinels. The isotherm evaluations revealed that the Freundlich model provides better fit to the experimental data than that of the Langmuir model. The photocatalytic degradation of RB5 at pH 1 under UV irradiation was examined. The results showed that the degradation of RB5 dye follows merely an adsorption process.     

"Off-On" Electrochemical Hairpin-DNA-Based Genosensor for Cancer Diagnostics

A simple and robust "off-on" signaling genosensor platform with improved selectivity for single-nucleotide polymorphism (SNP) detection based on the electronic DNA hairpin molecular beacons has been developed. The DNA beacons were immobilized onto gold electrodes in their folded states through the alkanethiol linker at the 3'-end, while the 5'-end was labeled with a methylene blue (MB) redox probe. A typical "on-off" change of the electrochemical signal was observed upon hybridization of the 27-33 nucleotide (nt) long hairpin DNA to the target DNA, in agreement with all the hitherto published data. Truncation of the DNA hairpin beacons down to 20 nts provided improved genosensor selectivity for SNP and allowed switching of the electrochemical genosensor response from the on-off to the off-on mode. Switching was consistent with the variation in the mechanism of the electron transfer reaction between the electrode and the MB redox label, for the folded beacon being characteristic of the electrochemistry of adsorbed species, while for the "open" duplex structure being formally controlled by the diffusion of the redox label within the adsorbate layer. The relative current intensities of both processes were governed by the length of the formed DNA duplex, potential scan rate, and apparent diffusion coefficient of the redox species. The off-on genosensor design used for detection of a cancer biomarker TP53 gene sequence favored discrimination between the healthy and SNP-containing DNA sequences, which was particularly pronounced at short hybridization times.     

Functional properties of acetylated glutenin and gliadin at varying pH values

Applications of glutenin and gliadin in food products are limited as they cannot provide desirable functional properties. The objectives of this study were to improve the functional properties of glutenin and gliadin by acetylation using acetic anhydride and to study these properties at pH 3, 6 and 9. Under the experimental conditions, about 53.88% of glutenin and 28.46% of gliadin were acetylated. pH of the medium and acetylation of the proteins affected water solubility, water absorption, water holding capacity, emulsifying and foaming properties of the samples. The results of the sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that high and low molecular weight glutenin subunits and ω-gliadins were affected by acetylation, while pH changes had no significant effect on the molecular weight of the proteins. Taken together, the results showed that acetylated glutenin and gliadin can be used as protein sources with good functional properties, particularly at alkaline pH.     

Synthesis,characterization, and measurement of structural,optical, and phtotoluminescent properties of zinc sulfide quantum dots

A facile and rapid microwave irradiation method was developed to prepare ZnS nanoparticles (NPs) using a set of ionic liquids (ILs) based on the bis(trifluoromethylsulfonyl) imide anion and different cations of 1-alkyl-3-methyl-imidazolium. The phases, structures, and optical absorption properties of the NPs were determined in depth with X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, UV–vis absorption spectroscopy (UV–vis), diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The average crystallite size of the ZnS NPs calculated from the XRD pattern was of the order of 2.8 nm which exhibits cubic zinc blende structure. The energy band gap measurements of NPs were carried out by UV and DRS. The results revealed that the ZnS NPs exhibit strong quantum confinement effect. The optical band gap energy increases significantly compared with those of the bulk ZnS. The refractive indices for different ZnS nanosamples and different concentrations of ZnS NPs for a typical sample suspended in deionized water were also measured.     

Ionic liquid ultrasound assisted dispersive liquid-liquid microextraction method for preconcentration of trace amounts of rhodium prior to flame atomic absorption spectrometry determination

In this article, we consider ionic liquid based ultrasound-assisted dispersive liquid-liquid microextraction of trace amounts of rhodium from aqueous samples and show that this is a fast and reliable sample pre-treatment for the determination of rhodium ions by flame atomic absorption spectrometry. The Rh(III) was transferred into its complex with 2-(5-bromo-2-pyridylazo)-5-diethylamino phenol as a chelating agent, and an ultrasonic bath with the ionic liquid, 1-octyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide at room temperature was used to extract the analyte. The centrifuged rhodium complex was then enriched in the form of ionic liquid droplets and prior to its analysis by flame atomic absorption spectrometry, 300 μL ethanol was added to the ionic liquid-rich phase. Finally, the influence of various parameters on the recovery of Rh(III) was optimized. Under optimum conditions, the calibration graph was linear in the range of 4.0-500.0 ng mL(-1), the detection limit was 0.37 ng mL(-1) (3S(b)/m, n = 7) and the relative standard deviation was ±1.63% (n = 7, C = 200 ng mL(-1)). The results show that ionic liquid based ultrasound assisted dispersive liquid-liquid microextraction, combined with flame atomic absorption spectrometry, is a rapid, simple, sensitive and efficient analytical method for the separation and determination of trace amounts of Rh(III) ions with minimum organic solvent consumption.     

Efficient Timing Budget Management for Accuracy Improvement in a Collaborative Object Tracking System

This paper presents the idea of managing the comprising computations of an application performed by an embedded networked system. An efficient algorithm for exploiting the timing slack of building blocks of the application is proposed. The slack of blocks can be utilized by replacing them with slower but cheaper, i.e. better, modules and by assigning the computations to the proper resources. Thus, our approach manages the comprising computations and system resources and can indirectly assist the realtime scheduling of computations on system resources. This is performed without compromising the timing constraints of the application and can lead to significant improvements in power dissipation, computation accuracy or other metrics of the application domain. Our algorithm is well-suited for arbitrary tree computations. Moreover, it delivers solutions that are desirably close to the optimal solution. Experimental results for a number of object tracking applications implemented in an networked system with embedded computation resources, exhibit a significant amount of slack utilization. Soheil Ghiasi received his B.S. from Sharif University of Technology, Tehran, Iran in 1998, and his M.S. and Ph.D. in Computer Science from the University of California, Los Angeles in 2002 and 2004, respectively. Currently, he is an assistant professor in the department of electrical and computer engineering at the University of California, Davis. His research interests include different aspects of Embedded and Reconfigurable system design. Elaheh Bozorgzadeh received the B.S. degree in Electrical Engineering from Sharif University of Technology, Iran in 1998, M.S. degree in Computer Engineering from Northwestern University in 2000, and Ph.D. degree in Computer Science from the University of California, Los Angeles, in 2003. She is currently as assistant professor in the Department of Computer Science at the University of California, Irvine. Her research interest includes VLSI CAD, design automation for embedded systems, and reconfigurable computing. She is a member of ACM and IEEE. Karlene Nguyen received her B.S. and M.S. from University of California, Los Angeles in 2001 and 2003, respectively. She has been working with Prof. Majid Sarrafzadeh for her M.S. degree. Her research interests include embedded hardware and software design. Majid Sarrafzadeh received his B.S., M.S. and Ph.D. in 1982, 1984, and 1987 respectively from the University of Illinois at Urbana-Champaign in Electrical and Computer Engineering. He joined Northwestern University as an Assistant Professor in 1987. In 2000, he joined the Computer Science Department at University of California at Los Angeles (UCLA). His recent research interests lie in the area of Embedded and Reconfigurable Computing, VLSI CAD, and design and analysis of algorithms. Dr. Sarrafzadeh is a Fellow of IEEE for his contribution to “Theory and Practice of VLSI Design.” He received an NSF Engineering Initiation award, two distinguished paper awards in ICCAD, and the best paper award in DAC. He has served on the technical program committee of numerous conferences in the area of VLSI Design and CAD, including ICCAD, DAC, EDAC, ISPD, FPGA, and DesignCon. He has served as committee chairs of a number of these conferences. He is on the executive committee/steering committee of several conferences such as ICCAD, ISPD, and ISQED. He is the program committee chair of ICCAD 2004. Professor Sarrafzadeh has published approximately 250 papers, is a co-editor of the book “Algorithmic Aspects of VLSI Layout” (1994 by World Scientific), and co-author of the book “An Introduction to VLSI Physical Design” (1996 by McGraw Hill). Dr. Sarrafzadeh is an Associate Editor of ACM Transaction on Design Automation (TODAES) and an Associate Editor of IEEE Transactions on Computer-Aided Design (TCAD) and ACM Transactions on design Automation (TODAES). Dr. Sarrafzadeh has collaborated with many industries in the past fifteen years including IBM, Motorola, and many CAD industries. He is the architect of the physical design subsystem of Monterey Design Systems main product. He is a co-founder of Hier Design, Inc.     

Numerical Modeling of the Freezing of a Porous Humid Food inside a Cavity due to Natural Convection

The conjugate heat transfer problem of food freezing inside a cavity was numerically investigated. A vegetable sponge has been considered as a food block freezing inside a square freezing chamber due to natural convection. The need for specifying the block surface convective heat transfer coefficients was eliminated by solving the surrounding cooling fluid and, therefore, a comprehensive understanding on heat transfer and airflow during freezing can be achieved. The 2-D unsteady Navier-Stokes and energy equations were solved using a finite volume method with the semi-implicit SIMPLE algorithm. Thermophysical properties of food block components were considered to be dependent on temperature, as well as moisture and ice content, which has been rarely considered in food freezing studies. The specific heat capacity method was employed to model the freezing process. The Krischer model was adopted for predicting the thermal conductivity of the food, which indicates that the model works with reasonable accuracy for humid porous foods. The mechanism of natural convection in the cavity was carefully studied and the effects of different parameters on the freezing time were examined. The food freezing curves were investigated for various Rayleigh numbers in the range of 10⁴ ≤ Ra ≤ 10⁶, with different area ratios of A = 1/16, 1/9, and 1/4, and food initial water contents of X _tw  = 0.48, 0.58, and 0.68. It was concluded that increasing the Rayleigh number reduces the freezing time. On the other hand, area ratio and initial water content of the food were proved to extend the freezing time.